In order to be able to utilize distance and velocity information of an anticipatory surroundings sensor in the passive safety system (passive safety application), the surroundings sensor must provide these data sufficiently quickly and at the right time. Camera-based systems often do not operate sufficiently quickly due to their long processing times. Therefore, they may pose a safety risk due to their delay times, e.g., when restraint means in the vehicle are actuated. In particular, camera-based systems require a minimum number of frames for the determination of a reliable relative velocity. Usually, distance estimation is performed on the basis of two camera images, and the associated time period between these two frames is used to calculate the relative velocity between two vehicles.
Outdated information, however, cannot be used in the passive safety system. In particular, the data provided by a slow surroundings sensor are hardly usable in a passive safety system in a useful manner in the event of the most typical of all driver's reactions prior to an accident, which is emergency braking with a deceleration approximating gravitational acceleration (9.81 m/s2).